Businesses or other entities having a need for volume printing typically purchase a production printing system. A production printing system comprises a high-speed printer used for volume printing, such as 100 pages per minute or more. The production printing systems are typically continuous-forms printers that print on paper or some other printable medium that is stored on large rolls. Some continuous-forms printers are able to print on paper up to 20 inches wide or more.
A production printing system typically includes a localized print controller that controls the overall operation of the printing system, and one or more print engines (sometimes referred to as an “imaging engine” or as a “marking engine”). The print engines include a printhead controller and arrays of printheads. An individual printhead includes multiple tiny nozzles (e.g., 360 nozzles per printhead depending on resolution) that are operable to discharge ink as controlled by the printhead controller. The printhead array is formed from multiple printheads that are spaced in series along a particular width, such as 20 inches.
When in operation, the printable medium is passed underneath the printhead arrays while the nozzles of the printheads discharge ink at particular intervals to form pixels on the medium. Some of the media used in inkjet printers is better suited to absorb the ink, while others are not. Thus, printing systems may be implemented with a radiant dryer unit that assists in drying the ink on the medium after the print engine discharges ink on the medium.
A typical dryer unit includes an array of lamps that emit light and heat to dry the ink onto the medium. The power applied to the lamps typically varies based on the speed of the medium as it passes through the dryer unit. As the speed of the medium increases, a higher intensity light is needed to dry the medium. In a traditional dryer unit, the power applied to the lamps of the array would increase as the speed of the medium increases. By increasing the power applied to the lamps, the intensity of the light produced by the array likewise increases to dry the medium. As the speed of the medium decreases, a lower intensity light is needed to dry the medium. Thus, the power applied to the lamps of the array would decrease as the speed of the medium decreases. By decreasing the power applied to the lamps, the intensity of the light produced by the array likewise decreases to dry the medium.
Printer manufacturers are continually trying to improve the effectiveness of radiant dryer units.